That is the question of the day in Argentina's most sensational murder mystery: the unsolved slaying more than six months ago of Nora Dalmasso, a mother of two who was strangled in her suburban home with the belt of her robe.

The case, with its intimations of sexual high jinks behind the walls of upscale gated communities called countries, generated O.J. Simpson-style blanket coverage and whodunit speculation in living rooms and cafes.

A relative lull in the drumbeat of breathless stories about Dalmasso ended abruptly this month with a stunning development: Her blue-eyed son, Facundo Macarron, 20, long depicted as a model law student who worshiped his mom, was charged with homicide and "aggravated sexual abuse" in his mother's death.

The sensational twist, with its suggestion of incest, reignited the media frenzy. Family lawyers proclaimed the son's innocence and labeled as deficient the evidence -- mostly DNA samples at the murder scene, reportedly including swipes from the cloth belt.

"Of course his genetic profile was in the house. The kid lived there," said a defense lawyer, Tirso Pereyra.

Some said the naming of the son as prime suspect could be the latest misstep in a mismanaged case that has resulted in the resignations of a dozen top cops and prosecutors and sparked street protests in Rio Cuarto, the affluent city on the pampas where Dalmasso lived and was killed.

The media reported that the son's alibi evaporated when his gay partner -- the son's apparent homosexuality was another revelation -- recanted statements that at the time of the killing, the two had been together in the university city of Cordoba, 125 miles away.

Prosecutors gave no hint of the son's alleged motive, though accounts surfaced of family discomfort with his lifestyle and a purported "oedipal" relationship with his mother.

When the story initially broke during the southern hemisphere summer, the steamy murder sparked unconfirmed reports of orgies, swingers and spouse-swapping in the exclusive Villa Golf, the gated neighborhood where Dalmasso resided with her husband, Marcelo Macarron, 47, a prominent physician, their son and 16-year-old daughter.

The singular micro-culture of Argentina's fast-growing gated communities, popular bastions for upper-middle-class families seeking relief from street crime and other urban woes, was long a source of societal fascination: People imagined covert mischief amid the spacious homes and manicured lawns of these hermetic enclaves, where all visitors must pass through security gates and register their comings and goings.

The elegant Dalmasso had seemed emblematic of the "country" woman: seemingly flawless wife and mother, successful entrepreneurial donor to good causes, participant in a dizzying social scene.

A neighbor found her nude body on a Sunday afternoon in late November, face up in her teenage daughter's bed. The cloth belt was double-knotted around her neck. She had been last seen Friday at a nearby restaurant with a circle of female friends, sipping champagne, the media reported. Police say she was probably killed sometime Saturday. Her family was away that weekend.

No valuables were missing, and the house was not in disarray. Dalmasso's clothes were folded neatly on a shelf in the upstairs bedroom where she was found, inside the family "chalet," as the Spanish-style home is inevitably described. Her Rolex was on her wrist. There was no sign of forced entry to the house.

An autopsy showed she had what police called "strong" sex before her murder, and possibly as she was being killed. Authorities said the sex appeared consensual.

This was a crime of passion, authorities declared, and Dalmasso probably knew her killer. She appeared to put up little resistance. One theory focused on a sex game simulating asphyxiation that had gone wrong.

The murder details seemed to bear out the most prurient rumors about decadence in "los countries."

At the time of the murder, her husband was away at a golf tournament in Punta del Este, the trendy Uruguayan seaside retreat favored by the Argentine gentry. He hastily returned and appeared with his two children declaring he refused to "judge" the private life of his wife, whom he called "the world's greatest mother." He lamented his frequent absences from home.

"I want the murderer of my wife found," the distraught husband said in a newspaper interview. "I can't live suspecting everyone."

Authorities zeroed in on Dalmasso's purported lovers. Some two dozen people gave DNA samples to be matched against swipes from the bedroom.

A house painter with a history of psychological problems was charged in connection with the crime in February. He was jailed amid great fanfare, then released the next day after 2,000 area residents protested that he was a patsy, a fall guy in a country with a dismal legacy of police corruption and incompetence.

Then, the scandalous affair gradually faded from the public eye -- until this month when Dalmasso's beaming smile reappeared in the media, the allegations about her son the latest chapter in a tawdry tale of lust and murder that continues to fascinate.